Method of and apparatus for making honeycomb core

ABSTRACT

A web of thin flexible material such as resin-impregnated cloth suitable for making expanded honeycomb core structures is drawn from a roll, the web being somewhat more than twice the width of the lay-up which is intended to be made. The double web passes through a printing station at which only one face has transverse lines of adhesive imprinted thereon. Each line extends only halfway across the web, and the lines on one half of the web are staggered along the length of the web with respect to the lines on the other half by a constant spacing. The web is slit into two halves, each being approximately one half of the width of the original double web. From the cutting station the two half webs pass over a pair of spaced turning bars which change the direction of movement of the respective half webs so that they are aligned edge to edge but with both printed faces in the same orientation so that the face of the bottom web engages the back of the top web.

[15] 3,655,475 1451 Apr. 11, 1972 Primary Examiner-Benjamin A. BorcheltAssistant Examiner-G. E. Montone Attorney-Silverman & Cass [57] ABSTRACTA web of thin flexible material such as resin-impregnated cloth suitablefor making expanded honeycomb core structures is drawn from a roll, theweb being somewhat more than twice the width of the lay-up which isintended to be made. The double web passes through a printing station atwhich only one face has transverse lines of adhesive imprinted thereon.Each line extends only half-way across the web, and the lines on onehalf of the web are staggered along the length of theweb with respect tothe lines on the other half by a constant spacing. The web is slit intotwo halves, each being approximately one half of the width of theoriginal double web. From the cutting station the two half webs passover a pair of spaced turning bars which change the direction ofmovement of the respective half webs so that they are aligned edge toedge but with both printed faces in the same orientation so that theface of the bottom web engages the back of the top web.

30 Claims, 7 Drawing Figures ....B3ld 3/02Budwig.............................,156/197 X ....l56/548 XBallard................ ...156/512 X 7/1962 Wentworth et al. ...156/197Bova et a1..............................156/197 United States PatentStelling, Jr. et al.

[54] METHOD OF AND APPARATUS FOR MAKING HONEYCOMB CORE [72] Inventors:Walter R. Stelling, Jr., Wauwatosa, Wis; Burton L. Siegal, Skokie, 111.;Michael M. Talbott, Key Biscayne, Fla. [73] Assignee: Orbitex, Inc.,Miami, Fla.

[22] Filed: May 26, 1969 [21] App]. No.2 827,781

[52] [51] Int. [58] FieldoiSearch..........................

[56] References Cited UNITED STATES PATENTS 412 7/ 1904 131 8/1953Lincoln...

PATENTEDAPR'II I972 3.655.475

SHEET u UF 4 Xmrim Z .Fzlega METHOD OF AND APPARATUS FOR MAKINGI-IONEYCOMB CORE BACKGROUND OF THE INVENTION 1. Field of the Invention IThe invention herein relates generally to the field of manufacturinghoneycomb core for use in fabricating honeycomb core structures. lt isconcerned with the process and apparatus which produce the so-calledlay-up just before expansion, such lay-up being a stack of sheets offlexible material properly oriented so that the lines of adhesive arearranged to produce the characteristic sixssided honeycomb cells whenthe stack is thereafter adhered to form a block and then expanded.

' The older methods of making honeycomb core material used webs thatwere imprinted with adhesive along their lengths so that the printingrolls were made as cylinders having circumferential parallel annularprinting rings and the adhesive lines were parallel with the side edgesof the web. Many methods of printing and handling webs were used, butthe result was the same. The web is cut into equal lengths and these arelaid on top of one another, but the lines of adhesive between each pairof facing sheets must be staggered with respect to lines of adhesivebetween either one of these sheets and the face of the succeeding sheetopposite. To be more explicit, and considering a group of sheets whichmay be designated A, B, C, D etc., on top of one another, the lines ofadhesive joining sheets A & B, C & D, E & F, etc., all lie on top of oneanother in perfect alignment. The lines of adhesive joining the sheets B& C, E & E, F & G, etc., also lie on top of one another in perfectalignment, but are located between the lines of the former group. Inother words the lines of adhesive on opposite faces of any sheet arestaggered. The lines of adhesive in the honeycomb core material areknown as node lines.

When a block of sheets so adhered is pulled apart, assuming properlychosen dimensions for the width of the adhesive lines and their spacing,there will result substantially perfect honeycomb cells, each of whichhas two oppositely parallel sides formed of adhesive lines secured toother cells, and the remaining four sides being free of face to faceattachment.

As known, the resulting structure has great strength in the direction T,which is perpendicular to the cells and has been used for the core ofaircraft and missile members, in furniture, doors and in many otherstructures. The materials from which honeycombcore is made comprisealuminum and steel foil, paper, resin-impregnated fiberglass cloth, andother flexible fibrous sheeting. In large structures it is desirable tohave the ribbon dimension L of the honeycomb core material asuninterrupted as possible without the need for piecing sectionstogether. This gives greater strength to the resulting compositestructure. The ribbon dimension L is the general direction defined by asingle sheet of material transversely of the cells but in the directionof the undulations forming the cells. Thus, for example, in the case oflengthwise printing of adhesive, the node lines will be formed along thelength of the web, the cells will have their axes also along the lengthof the web, but the ribbon dimension L will be transverse of the web.Accordingly the maximum ribbon dimension for a given block of expandedhoneycomb (called a log in the trade) is the width of the web from whichit is made. The W, or width dimension is also at right angle to thecells, but also normal to the ribbon dimension. The honeycomb core hasless strength in the W'dimension than the L dimension.

In the case of transverse printing of the adhesive lines, the resultingnode lines will be transverse of the log, and the ribbon dimension Lwill be along the length of the log. The T dimension is determined bythe width of the web, and this is normally very small because of thethickness of members eventually made. There is no limitation to ribbondimension L other than the practical problems of handling materials ofgreat length.

Others have realized the benefits of transverse printing, but thus farthe methods and apparatus for utilizing the technique are not efficientand economical. Aside from the normal problems of controlling the sidelay and registration of webs passing through printing machinery, theproblem of accurately laying the lengths of cut web material one on topof the other to produce a proper lay-up has been difficult to solve.Various schemes of interleaving, cutting successive or alternate sheets,and the like have been attempted. These require expensive and complexapparatus, special formulas to be used in computing the proper lengths,etc.

The invention contemplates a simplified and effective method of andapparatus for producing the lay-ups for making honeycomb core materialwhich are based upon the use of a single, wide web that is imprintedwith two patterns side by side, these patterns being accurately relatedso that when the two webs arecut at the same point and placed on top ofone another there will be accurate staggered orientation of the adhesivelines with respect to one another. The exact nature of the inventionwill be described hereinafter.

2. The Prior Art It is known to print adhesive lines transversely of aweb of flexible material to obtain the benefit and advantages of thelonger ribbon dimension.

The following patents disclose this well-known concept:

Lincoln U.S. Pat. No. 2,649,131; May U.S. Pat. No. 3,074,839; Knoll etal. U.S. Pat. No. 2,983,640; and Bova U.S. Pat. No. 3,242,024.

Engel U.S. Pat. No. 2,609,315 discloses the concept of making honeycombcore material in which the web is corrugated prior to adhering to otherwebs, the corrugations being transversely of the length of the web.

SUMMARY OF THE INVENTION The invention herein is characterized by theprocessing of a double web as opposed to the prior art processing ofsingle webs. The adhesive line pattern is printed on a double width webwith the lines of the respective patterns staggered. Each pattemhas aline of perforations along one edge thereof the perforations beingpaired on the respective patterns and precisely located, but notnecessarily being geometrically disposed with respect to each line ofthe patterns. In this way the same perforating mechanism may be used fordifferent cell cizes.

In the double form and with the perforations, the web passes through adrying oven where the printed adhesive is dried to a temporarynon-adhering condition, and then if desired, the web passes through somecooling means, such as for example, between chilling rolls. Thereafter,the web is led through a slitting station using, preferably, a pair orpairs of rotating cutting wheels. One cut divides the web in half alongits central length and another cut trims off the edge. This is done toprovide cut sheets with some reference edge so that variations of theactual transverse dimension of the web will result in a minimum of outof register sheets in a given lay-up.

Following the passage of the double web through the slitting station,the respective halves are separated angularly, that is, along divergingplanes but without lateral separation so as to eliminate strain on therespective webs. In the preferred embodirnent, each half web passes overa turning bar which is arranged at an angle, the turning bars beingspaced apart vertically but being arranged at substantially the sameorientation to that the two half webs which leave their respectiveturning bars will be in lateral alignment, but, spaced one above theother. One of the half webs is adjusted in length by means of a suitablecompensator mechanism and thereafter joins the other web substantiallyin registration therewith, the double thickness presented by both halfwebs being passed through a pair of draw rollers and into a sheeter. Thesheeter includes a rotating knife that cuts the sheets simultaneouslyinto any.

predetermined length, the length being chosen so as to provide a repeatlength which will besynchronized with the location of the perforations,the perforations by this time being substantially in alignment. Thesheets are accumulated in a suitable container, and when a sufficientnumber has been accumulated, the sheets are lifted out of the containerand spindled onto a single pin provided on a board driven by a jogger oronto a plurality of pins. A guide is used to cooperate with the joggerto stack the sheets and thereafter the stack may be clamped and moved tofurther processing.

In anotherform of the invention, one of the half webs is led over a pairof turning bars which are spaced apart to lead the said half web to adisposition overlying the other unturned half web so that both mayproceed together through the sheeter on the same path as the unturnedhalf web.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is perspective diagrammaticview in highly simplified form showing the apparatus used in practicingthe method of the invention.

FIG. 2 is a diagrammatic top plan view of the jogger of FIG. 1 with alay-up of cut sheets in place thereon.

FIG. 3 is a fragmentary top plan view of a section of web takenapproximately at the location of the arrows 2-2 of FIG.

FIG. 4 is a fragmentary sectional view diagrammatically illustrating theupper left hand corner of the stack being formed on the pin of FIG. 2.

FIG. 5 is a fragmentary perspective view of a portion of the apparatusof FIG. 1 but illustrating a modified form of such apparatus.

FIG. 6 is a top plan view of the structure shown in FIG. 5.

FIG. 7 is a fragmentary diagrammatic view of apparatus for performing amodified method in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic method of theinvention depends on performing some of the important processes whilethe web of flexible material is twice as wide as the eventual lay-up.This gives rise to efficiency and economy as well as ease of handling.Registration problems are substantially decreased and uniformity isfairly well assured.

The reference character 10 in FIG. 1 designates generally apparatus forcarrying out the invention. It will be appreciated that respectiveportions of the apparatus are well known as to their generalconstruction and characteristics and it will also be appreciated thatcertain devices which are used in handling webs and printing on them arenot illustrated. These will be pointed out.

A roll of flexible sheet material is illustrated at 12 and this is shownmounted on a suitable shaft 14, being arranged to have a double widthweb 16 unwound therefrom. The shaft 14 symbolically represents any typeof unwinding apparatus which will support the roll 12. The materialwhich is capable of being used in any of the fabrics or foils from whichhoneycomb core structures are made and will include aluminum foil, wovenglass fabric impregnated with resin, and the like. One advantage of theinvention resides in being able to use large rolls which do notnecessarily require pre-slitting with resulting waste before use.

The raw web 16 passes through suitable guiding and feeding means such asfor example represented by the rolls l8 and 18' to the printing station20. Such guiding and feeding means may comprise a series of idlerrollers 18 for stabilizing the web being stripped off the unwindingapparatus 14 and a series of driven in-feed rollers 18'. Combinationsand variations may be used. The drive for the in-feed rollers issynchronous with the drive means for other parts of the apparatus 10. Inthe description of the apparatus hereinafter reference will be made toother guide rolls which assist in moving the web through the apparatus10. It will be appreciated that the illustration of guide rolls in FIG.1 and in FIG. 5 and 6 is merely diagrammatic, such guide rollssymbolizing some means for leading and directing the movement of theweb. Any apparatus handling long lengths web will have various types ofguiding means and hence it is to be understood that the illustration ofrolls and their locations is not intended to be limiting or to designateany specific guide means.

At the printing station 20 the raw web 16 has a pair of patternsimprinted thereon. These patterns will be described in detail shortly.The printing station may include a well 22 having a pickup roller 24applying a suitable adhesive which is carried in the well 22 to aprinting roller 26. A doctor roller or blade 28 wipes the surface of theprinting roller 26 after which the surface engages the bottom of the rawweb 16 and by virtue of the back-up roller 30 applies the patterns tothe raw web so that a double width imprinted web l6-P emerges from theprinting station 20. The double width printed web 16-? passes to aperforating station 32 at which the web l6-P is perforated by a suitablepunch and die arrangement. For purposes of simplicity there isillustrated a roll 34 having punches and a second roll 36 having theso-called dies into which the punches telescope so that the web passingout of the perforating station 32 is now printed and perforated. The webis thus designated 16-PP. Such web is shown passing over successiveguide rolls 38 and 40 to enable its direction of movement to be changedand then passing through a drying station 42.

The perforating station 32, according to the embodiments of theapparatus and the method thus far described in connection with FIG. 1,is required to handle the printed web 16-? on which the lines of theadhesive are still wet. This does not pose a problem for certainapparatus but, in case it does, it is simple matter to dispose theperforating station 32 before the printing station 20, such as forexample at the location designated 32. Thus, the wet printed webemerging from the printing station will also be perforated, and the rawweb 16 entering the perforating station 32' will be dry.

In respect to the type of adhesive and the nature of the printing roll26, for the production of accurate adhesive lines it is preferred that agravure method be used. The roll 26 adhesive lines therefore is engravedor etched with the desired pattern, the doctor device 28 wipes off theexcess adhesive from the surface of the roll 26 and the back-up roll 30actually presses the bottom of the web 16 against the surface of theroll 26 so that the adhesive is picked up out of the liens engraved onthe print roll 26. This method of printing is called direct gravure andprovides the best results for the honeycomb core material being madeaccording to the invention. Other printing methods may be used.

Referring now to FIG. 3 there is illustrated a short length of thedouble web 16-PP occurring for example at the location 2--2 of FIG. 1.But for the fact that the adhesive lines are dry at the location 2-2,there is no visible difference in appearance of the web between theperforating station 32 and the slitting station 44. The slitting stationwill be described below. The web length shown in FIG. 3, has beenreferred to as a double width web printed and perforated. There are twopatterns printed on the web l6-PP each pattern being a series of linesof adhesive which eventually will form node lines. The pattern 46-A isidentical to the pattern 46-B with the exception that the individuallines of adhesive do not extend uninterruptedly across the web 16-PP.Importantly the track for the perforations must be clean, in almost allcases, to prevent adhesive from interfering with the perforating means.The lines 48 of each pattern are identical in length, thickness, widthand spacing and are staggered with a precise half-pitch spacing so thatif the web 16-PP is slit up its center on a line 50 and the webs placedon top of one another without changing the longitudinal orientation ofthe lines, the lines of the adhesive of the one half of the web will lieexactly between the lines of adhesive of the other half. This will beappreciated from an examination of FIG. 4, although FIG. 4 relates tothe spindling of the cut sheets to be described. The requirement ofalternate lines of adhesive to form the node lines between sheets whichwill be pulled apart to produce honeycomb is well-known and fullydescribed in the prior art. The dimensions of the primed lines ofadhesive and their relationship to one another are chosen to producecells of six-sided configuration. All lines 48 have the same ribbondimension 52, the same pitch 54 being chosen so that when sheets areadhered together the adhesive lines 48 will produce the nodes and thespaces there between will produce the single thickness unadheredportions of the honeycomb cells. Due to practical considerations andgeometry, the distance 56 between the printed lines 48 of the pattern isnot exactly equal to three times the L dimension 52 of the printedlines.

As for the length of the lines 48 considered transversely of the web16-PP, it will be seen that such length 58 will be the same for eachpattern. There is a line of perforations 60-A on the web half A, thecenters of such perforations 60A being on a line 62-A spaced from theline 64-A which represents the left hand ends of the adhesive lines 48of the pattern 46A. Likewise, the right hand half of the web l6-PP hassimilar perforations as 60-B lying on the line 62-B spaced from the line64-B by the same amount as the spacing between the lines 62-A and 64-A.The perforations occur along clear tracks, preferably.

The perforations 60-A and 60-B are identically located on each half ofthe web 16-PP so that each perforation forming a pair, that is, with oneon the right half and one on the left half, lies at the same identicalpoint along the length of the web l6-PP. This is indicated by lines60-C. The perforations are spaced equally apart along the length of theweb by the pitch distance indicated at 66 this being chosen so thatthere will be a repeat pattern coinciding at some point with identicalappearance of the repeat pattern of the printed lines 48. This can bedone by suitable choice of the dimensions of the printing roll 26 andthe dimensions 52, 54 and 66.

Referring once more to FIG. 1, the moving web 16-PP passes through thedrying station 42 where the adhesive is dried to a substantiallynon-adhering condition. This is so that the sheets may be handled andstacked without difficulty of adhering, since there are adjustmentswhich normally would be made by moving sheets relative one to the otherduring the process. Resinous adhesives are preferred since these may bedried temporarily, and the adhesive later activated by heat and/orpressure. 1

The web l6-PP emerges from the drying station 42, passes over a guideroll 70 to the slitting station 44. If desired, the web l6-PP may becooled after it emerges from the drying station in a cooling station 72by passing the same over so-called chill rolls 74 which have circulatingcoolant as shown at 74'. The web 16-PP may also be cooled by air ifdesired or even handled without further cooling prior to entry into theslitting station 44.

At the slitting station 44 the web l6-PP passes around draw and/or pinchrolls 76 to the slitting means 78. Two rotating knives 80 and 82 areshown in simplified form co-operating with a backup structure 84, theseknives serving to cut and trim web 16-PP so that when the web emergesfrom between the draw or pinch rollers 86 it is comprised of a left handweb l6-PP-A, a right hand web 16-PP-B and a small strip of waste l6-PP-Wwhich is trimmed off during the process and passes into a suitablereceptacle 88.

Referring now to FIG. 3 once more, it will be noted that the lines ofcutting by wheels 80 and 82 are designated by 90 and 92 respectively. Itwill be recalled that the half web dimensions A and B were said to besubstantially equal. It is preferred that the cut lines 90 and 92comprise the reference edges of the resulting sheets so that the effectsof any drift in the lateral position of the web 16 as it passes throughthe apparatus will be minimized. This will become apparent when thedescription relates to the matter of making the layup. Sidelayapparatus: mechanical, electrical, hydraulic, pneumatic and combinationsthereof; are known, and commercially available for controlling theaccurate passage of the web 16- PP through the apparatus 10 withoutsubstantial lateral drift.

From the slitting station, the two webs 16-PP-A and l6-PP-B separatealong two diverging planes which are at an angle to one another butwithout changing the lateral reference of one web to the other. Theinside edges 92 and 92' of the separating webs both lie in the same flatplane that is normal to the axes of the last guide roll engaging thewebs after slitting. In FIG. 1 these would be the draw or pinch rolls86. This arrangement prevents lateral strains on either of the webhalves 16-PP-A and 16PP-B.

The next step in the method of the invention and which is required to beperformed by the apparatus is to bring the two webs together in face toback relationship and with the printed surface of one web engaging theblank surface of the other. This is done at a turning station 93, therebeing a pair of turning bars 94 and 96 at such a station. These bars maybe any known structure, and in the preferred device they were highlypolished, fixed, generally cylindrical members arranged atan angle withrespect to the approaching webs l6-PP-A and l6-PP-B and spaced apartvertically. In this instance the resulting half-webs 16-PP-A and l6-PP-Bafter turning, were both approximately as with respect to the directionof movement prior to turning, but this is a matter of choice since thewebs can be turned by means of such turning bars to come together in anydirection of movement. Each web half passes over its respective bar andas emerging from the turning station 93, the printed patterns are on thebottom as shown in FIG. 1. Thus, the lines of perforations are on theleft of the web as shown at 60-A and 60-B. The web 16-PP-A is the bottomone. The web halves may be turned right or left, as desired, and eithermay be on top or bottom.

In order to compensate for any difference in total length of therespective webs from the slitting station 44 to the sheeter 98, acompensation device 99 conveniently may be provided operating on one ofthe webs. In FIG. 1 the web l6-PP-A passes from its turning bar 96 tothe laminating guide roll 101 directly. The half web 16-PP-B however,first passes around a guide roll 102 whose shaft axis is fixed and thenover a compensating roll 104 which is adjustable bodily by having itsaxis vertically movable so that a loop 106 is formed in web 16-PP-B.This loop may be increased or decreased as desired to bring the two webs16-PP-A and 16-PP-B into substantial registration by the time both ofthem pass around the laminating roll to the pinch and draw rolls 108.These two latter rolls may be considered a part of the sheeter 98.

At 109 there is shown in block form an apparatus which may occur priorto or after the pinch rolls 108 and having a cable 111 which is shownextending to control means. In operating the compensating device 99 theroll 104 is raised or lowered. This can be done mechanically by aworkman watching the perforation registration after the half webs cometogether, either between the roll 100 and the pinch rolls 108, or at thelocation where the device 109 is shown in FIG. 1. Preferably this can bedone photoelectrically. The device 109 directs a beam of light throughthe perforations and two photo-responsive transducers receive the lightin substantially equal amounts when the perforations are aligned. Theoverlap of perforations results in one or the other receiving more orless light. Suitable electrical equipment energizes means to move theroll 104 up or down. This type of equipment is known. The control mayalso be coupled to operate the rotating drum 1 10.

The sheeter is intended to cut the now doubled web 16-PP-A-B into sheetsof pre-determined length. There is illustrated a simplified rotatingdrum 110 having a radial knife 112 that cooperates with a backup roll114 so that each rotation of the drum 110 will produce a cuttransversely of the double web l6-PP-AB enabling the resulting pair ofsheets to be drawn through the discharge rollers 116 and be dischargedinto the movable bin 118.

All of the important rotating parts of the apparatus 10 are suitablesynchronized by means of drive mechanisms which are driven from a commonpower source (not shown). Thus for example, infeeding, printing,perforating, slitting and sheeting will have the rolls for the most partdriven by connection gears, chains, and the like. In the case of thesheeter, the

pull rolls 108 would be driven at slightly greater than the same speedthat the other rolls are driving the webs to maintain tension thereon.This may be true likewise of the rolls 116. As for the drum 110, itsspeed is controlled by a variable speed mechanism (not shown) controlledby the operator or automatically so that it revolves at such speedrelative to the rate of passage of the double web 16-PP-AB to give thedesired length of sheet.

The sheeter is arranged to cut at a repeat length that will provide thesame end edge relationship to the respective patterns 46A and 468 onevery sheet coincident with the occurrence of a repeat relationshipbetween perforations 60-A and 60-8 at the same location. This assumesnominal registration of perforations. Thus, the perforations resultingat any place along the pair of sheets will enable the sheets to beproperly aligned for making the necessary lay-up.

When a sufficient number of pairs of sheets has been accumulated in thebin 118, the stack such as indicated at 120 is transferred to the board122 of a jogger 124. Preferably, the bin 118 is on small casters 126arranged to roll along guide rails 128 maintaining the bin at an angledownwardly away from the sheeter so that the sheets emerging from thesheeter 98 will drop by gravity into the bin 118. When filled, the binis simply rolled into the position shown at 118' and a new bin placed atthe location to receive the discharged sheets so that the apparatus 10need not be interrupted for any substantial time.

The jogger 124 vibrates the stack 120 to align the sheets. In FIG. 2 thejogging board 122 is shown, this being at an angle with the horizontalof approximately 5 to and having a lower guide member 130 along one edgeAt its upper left hand corner, the jogging board 122 has a perpendicularspindling pin 132, this being located to engage one of the end, or closeto end perforations of the stack of sheets 120. The lower referenceedges 92 and 90 are aligned against guide 130.

In removing the stack 120 from the bin 118 as viewed in FIG. 1, sincethe sheets have their upper faces blank and the perforations 60-A and60-B are on the left as viewed in that figure, it is convenient torotate the stack as it is removed and as indicated by the arcuate arrowfor spindling operation. After the stack has been built up on thejogging table 124 it is clamped or otherwise secured together or couldeven be removed with the board 122 bodily to provide the completed blockor stack of unexpanded honeycomb illustrated at 136.

The flipping of sheets as described is to ensure that no pairs will besplit, as might be the case if sheets were removed and stacked elsewhereerectly. It is not essential to use the rolling bins 118. One could havea jogger right at the discharge of the sheeter and build the stack 120right at that point. Also where the automatic control gives goodperforation register, one could easily stack by using a bin having aplurality of stacking pins, instead of the scheme described, which usesa combination of one pin 132 and a guide 130 engaging the referenceedges 90 and 92.

This stack or block is placed under pressure, passed into an oven andheated so as to activate the adhesive and cure the same after which thestack is expanded by any suitable or well known mechanism. Expansionwill be effected vertically but obviously the stack may be otherwiseoriented during expansion relative to the stack shown in FIG. 2.

Assuming the top sheet in FIG. 4 to be one of a pair cut by the sheeter98, and realizing that the stack 120 has been turned up side down tospindle the same, it will be seen that the top sheet in FIG. 4 isderived from the web 16-PP-A, the next sheet from the web 16-PP-B and soon and it will also be noted that each of the sheets has the adhesivelines 48 thereon staggered when compared to the adhesive lines on itsadjacent sheet.

Considering FIG. 2, it should be appreciated that if there is a slightdifference between sheets in their widths because of slight lateraldeparture of the web from its normal line of passage through theapparatus 10, that amount in a stack 120 will be negligible, because asseen the dimension 62A to 90 is always substantially equal to thedistance between 628 and 92 even where the web drifts. Gradual driftwill not substantially change the register in the ribbon dimensions anyappreciable amount. Each sheet is rotated around its upper left handcomer so that both reference edges and 92 are engaged against the guidemember 130. There will be substantially no variance in length betweeneach of the sheets forming the pair since they are both being cut by thesheeter simultaneously.

The apparatus described thus far is conveniently used where theavailable floor space permits the equipment being arranged substantiallyat an angle. In other words the sheeter 98 has the web l6-PP-AB passingthrough it on a line which is substantially perpendicular to the line ofmovement of the webs passing out of the slitting station 44. Anestablishment where the apparatus is located may prefer that the linealong which the webs move be rectilinear beginning to end and in suchcase the structure of FIG. 5 may be used.

In FIGS. 5 and 6 the webs 16PP-A and 16-PP-B are shown on the rightemerging from a slitting station 44 (not shown in this view) and passingunder a guide roll 86 after which they diverge vertically. Again theedges 92 and 92 lie in the same vertical plane, but in this case the web16-PPA continues along the same line of movement to the sheeter (notshown) by way of the laminating guide roll 101. In this view thecompensating mechanism is not shown for simplicity. The web 16-PP-Bhowever, passes over two turning bars which are here designated 94' and96 whose purpose it is to move the web 16-PP-B laterally so that it liesdirectly on top of the web 16-PP-A. The turning bars 94 and 96' arearranged at an angle and vertically spaced and it is believed that theirfunction in effecting the result desired is obvious.

Each pattern may have different forms of indicia as at -A and 100-B toassist in visual identification to assist in identification of side byside half-webs for a multiplicity of maintenance and adjustmentpurposes.

It will be appreciated that the apparatus illustrated will normally havestructure well known in the trade that is common in the handling ofmoving webs. Electronic registration and compensating mechanism can beused, but according to the invention are not essential. Since the twohalves of the web are printed side by side and perforated side by side,the spindling on both perforations of an exactly located pair ofopposite perforations is bound to produce substantially perfectplacement of the printed patterns staggered with respect to one anotherexactly as printed. By choosing the proper repeat pattern at which pointthe sheeter 98 cuts the sheets lengthwise, registration of the lines isassured from pair to pair when the pairs are stacked onto the spindlingpin 132.

The apparatus and method which have thus far been disclosed relate to aweb which is imprinted on one face and unprinted on its back surface.Two variations of this scheme are worthy of mention.

In one example, the pattern 46A is imprinted on the one half of the faceof the web while the pattern 468 is imprinted on the other half of theback of the web. The dividing of the web and directing the two halves tomove into face to back engagement is accomplished in this instance byfolding the web up its center and swinging the two halves into surfaceto surface engagement about the fold. The nature of this method will beunderstood from a study of the discussion above, and apparatus foraccomplishing the same is capable of being devised by those skilled inthis art.

The second example utilizes a method and apparatus which will vary fromthose methods and apparatus detailed above by little. In this case,quite simply, the patterns are printed on both sides, a blank web islaminated to one surface prior to perforation and the laminated two-plyweb being thereafter treated exactly as a single ply web. In FIG. 7 theapparatus 200 has a first roll of flexible material at 212 on anunwinding apparatus 214 and providing a web 216 passing through guideroller means 218 and in-feed rolls 218' to the printing station 220. Inthis case there are two fountains 222, two pick-up rollers 224, twoprinting rollers 266 two doctor rollers 228 and two back-up rollers 230.This arrangement will print patterns on both faces of the singlethickness web 216 and the patterns will be exactly as described inconnection with FIG. 3, but staggered front and back. In other words,the pattern on the back of the half that carries the face pattern 46Awill be staggered but identical thereto, and hence identical inlength-wise disposition with respect to the pattern 468. The pattern onthe back of the half that carries the face pattern 463 will be staggeredbut identical therewith and hence identical in lengthwise dispositionwith respect to the patterns 46A.

The two surface printed web 216 is now passed through laminating rollers231 where it is laminated to another web 217 which is derived from asecond roll 212' passing through guide roll means 218" and in-feedrollers 219. The laminated web passes through a perforating station at232 which is identical to the station 32. After emerging from theperforating station 232, the laminated web has the same characteristicsas the web 16 described as 16-PP, that is, it has a pair of staggeredpatterns on one face and is blank on its rear surface or back. It canthereafter be passed through a drying station, chill rolls, slitter,turning station, etc. and handled exactly as though it was made out of asingle ply of flexible web material. When finally discharged from thesheeter, each pair of sheets will actually comprise a total of fourplies, but the resulting product will be no different than if itcomprises two plies. Thus reference to a blank surface does not excludea web having a ply of flexible material covering a printed pattern andpresenting an outward unprinted appearance. An additional drying stepmay be required as shown at 270 between the printing stations, toprevent wet adhesive from interfering with the operation of the secondprinting station, but this depends on the adhesive characteristics.Likewise the lamination could be done to the already printed sidebetween printing stations, which might eliminate the need for drying at270, leaving the full drying step for a later point in the process.

Modifications in the method and apparatus may be made without departingfrom the spirit or scope of the invention as defined in the appendedclaims.

What it is desired to be secured by Letters Patent of the United Statesis:

1. The method of making honeycomb core structure in a stack suitable forfurther processing by at least expanding the same, which comprises:

A. imprinting parallel lines of adhesive transversely of an elongatesubstantially continuously moving web of flexible material suitable formaking honeycomb core structure, said parallel lines i. being imprintedas two spaced side by side patterns, each pattern being continuous alongthe length of the web, occupying substantially half of the lateral widthof the web, and being disposed only on one face of its respective halfwidth with the back of said half width being unprinted,

ii. each pattern having its lines staggered with respect to the lines ofthe other pattern along the length of the web,

B. dividing the web substantially along the center to form two half webseach provided with one of said patterns only on one face thereof,

C. directing the two half webs angularly one relative to the otherdivergingly and then convergingly' to move same into surface to surfaceengagement one over the other with the pattern carrying face of one halfweb engaged with the unprinted back of the other half web butmaintaining the said staggered disposition of the lines of one patternwith respect to the lines of the other pattern substantially unaltered,

D. cutting equal lengths of the two webs simultaneously at apredetermined repeat location to provide pairs of face-toback sheets ofsaid flexible material of substantially half the width of the saidoriginal web,

E. accumulating and stacking said pairs of sheets into a stack whilemaintaining at least the same cut ends of each pair as a reference forsaid stack.

2. The method as claimed in claim 1 in which the two patterns aredisposed on the same face of the moving web.

3. The method as claimed in claim 1 in which the direction of movementof at least one of the half webs is changed after division to convertthe moving half webs from side-by-side disposition to a dispositionwhich will bring them into said face-to-back engagement.

4. The method as claimed in claim 2 in which said dividing isaccomplished by slitting, and in which said directing is effected bydiverting at least one of said half webs independently of the other toconvert the side-by-side disposition of said half webs to dispositionswhich will bring them superposed into said face-to-back engagement, oneof said half webs being laterally shifted relative the other.

5. The method as claimed in claim 4 in which both half webs are turnedon different levels and in'which the half webs are brought intoface-to-back engagement both moving in a directional path that isangular with respect to the path of both half webs prior to thediversion of either.

6. The method as claimed in claim 4 in which only one of said half websis turned whereby the directional path of both half webs when in saidface-to-ba ck engagement is not substantially different from the laterallocation of the path of the unturned half web after dividing.

7. The method as claimed in claim 1 in which said web is perforatedprior to dividing along the same respective edges of both patterns withthe perforations lying in a line spaced from said one pattern equallyalong the length of said web and with the perforations equally spacedapart each perforation having a companion located at an identical pointalong the length of the web but laterally spaced from itself wherebythere will be pairs of perforations along the length of the web, and theperforations having a repeat grouping that recurs at a rate capable ofbeing synchronized with the said repeat locations at equal points alongthe length of the web, the perforations of each cut sheet also aligningwith the perforations of its companion forming the pair of sheets sothat when said pairs of sheets are cut at one of said points, theperforations of any one pair will be registrable with the perforationsof all other pairs to enable alignment by spindling during stacking.

8. The method as claimed in claim 7 in which the perforating is donebefore imprinting.

9. The method as claimed in claim 7 in which the perforating is doneafter imprinting.

10. The method as claimed in claim 4 in which the said web is perforatedprior to dividing along similar edges of the respective patterns, therebeing a line of individual perforations along each such similar edge,the perforations being identically equally spaced along the length ofthe web and located at identical points along the length so that eachperforation has an identical perforation spaced laterally thereof toform therewith a pair, one of each pair of perforations being alongsideof the respective patterns, the perforation pairs having a repeatgrouping that recurs at a rate capable of being synchronized with thesaid repeat locations at equal points along the length of the web, sothat when said pairs of sheets are cut at one of said points, theperforations of any one pair will be registrable with the perforationsof all other pairs to enable alignment by spindling during stacking.

11. The method as claimed in claim 4 in which said slitting is effectedby slitting along two lines, one slit line being spaced laterally apredetermined distance from one edge of the web and having one patternbetween it and said edge and located between the two patterns, the otherslit line being substantially the same predetermined distance from theone slit line and having the second pattern between it and the firstslit line and being closely adjacent to the second edge of the web,whereby the cut sheets of each pair will be substantially the same widthnotwithstanding lateral drift of the web.

12. The method as claimed in claim 10 in which the line of perforationsof one pattern is located adjacent one edge of said web between said onepattern and said one edge, and the line of perforations of the otherpattern occurs between the said other pattern and the center of said webwhereby when so slit, each half web will have one line of perforationsalong the similar edge thereof.

13. The method as claimed in claim 12 in which said slitting is effectedby slitting along two lines, one slit being spaced laterally apredetermined distance from said one edge of said web whereby to havesaid one pattern and one line of perforations between it and said oneedge and being located substantially at the center of the web betweenthe two patterns, the other slit line being substantially the samepredetermined distance from the one slit line and having the secondpattern and second line of perforations between it and the first lineand being closely adjacent the second edge of the web, whereby the cutsheets of each pair will be substantially the same width notwithstandinglateral drift of the web.

14. The method as claimed in claim 13 in which the said one edge andsecond slit line of each pair of sheets are used as lateral referencesin stacking said sheets.

15. The method as claimed in claim 14 in which said sheets are joggedwhile stacking.

16. The method as claimed in claim 15 in which said sheets are spindledinto at least one perforation of each sheet at an end thereof duringstacking and jogging.

17. The method of making honeycomb core structure in a stack suitablefor further processing by at least expanding the same, which comprises:

A. imprinting parallel lines of adhesive on the face and transversely ofan elongate substantially continuously moving web of flexible materialsuitable for making honeycomb core structure, said parallel lines beingarranged in two independent patterns on respective lateral halves of theweb with the lines of one pattern staggered relative to the lines of theother,

B. slitting the web up its center to divide the same into two half websmoving side by side,

C. turning the half webs relative to one another diverting at least onefirst in a plane diverging relative the other and then in a planeconverging relative the other so as to bring the half webs intolaterally aligned face to back engage ment with one another with theface of one engaging the back of the other,

D. cutting predetermined lengths of the engaged sheets simultaneously,

E. accumulating the sheets to form a stack of aligned sheets referencedfrom a cut end thereof.

18. The method as claimed in claim 17 in which the patterns areimprinted on the face of the web only and the back of the web isunprinted.

19. The method as claimed in claim 18 in which the adhesive is resinousand the web is temporarily dried prior to slitting but is capable ofbeing heated to activate the adhesive to a permanently adheringcondition after stacking.

20. The method as claimed in claim 19 in which the web is temporarilydried by heating and is thereafter cooled prior to slitting.

21. The method as claimed in claim 18 in which the web is perforatedprior to slitting along a pair of lines of perforations, each line beingspaced laterally of one another and having equal spacing along thelength of the web, with the individual perforations of one line havingidentically laterally located perforations in the other line, each linebeing equally laterally spaced relative to one pattern and having arepeat grouping capable of being synchronized with the repeat of thepatterns to enable the use of said perforations for registration duringstacking.

22. The method as claimed in claim 17 in which the back of the web isimprinted with the identical patterns but each back pattern is staggeredwith respect to the pattern on its face half and with respect to itscompanion pattern on back half of the web, and in which a blank web islaminated to one of the face or back before slitting.

23. Apparatus for making honeycomb from flexible sheet material,comprising:

A. means for mounting a roll of raw sheet material and feeding andguiding the same in a substantially continuous movement through saidapparatus,

B. a printing station for applying adhesive lines to said web andcomprising a printing roll having axially extending printing lines intwo axially spaced continuous patterns with the lines of said patternsstaggered one relative to the other whereby to print two side by sidepatterns staggered on one surface of said web as it passes said printingstation,

C. a drying station having the imprinted web passing through the same,and serving to dry temporarily the adhesive imprinted thereon,

D. a slitting station having means for slitting the web up its center toform two half webs, each with a pattern on one face thereof and beingblank on the back thereof,

E. a turning station for angularly diverting at least one of said websto change the side by side disposition of said half webs to a laterallyaligned face to back disposition, said turning station including atleast one pair of half web direction-changing turning bars and at leastone of said half webs being directed to move divergingly from the otherand thereafter turn to shift laterally and convergingly relative to theother,

F. means for laminating the two half webs in said face to backengagement with the imprinted face of one engaging the blank back of theother,

G. a sheeter receiving the laminated half webs from the laminating meansand arranged to cut the same simultaneously in predetermined lengths anddischarging same in pairs and,

H. means for accumulating the cut sheets for stacking.

24. The apparatus as claimed in claim 23 in which means are provided foradjusting the relationship of said patterns to maintain their originalstaggered relationship along their lengths after having been separatedby slitting and prior to laminating.

25. The apparatus as claimed in claim 24 in which perforating means areprovided for applying a line of perforations adjacent each pattern alongthe same edge thereof prior to slitting so that each half web has a lineof perforations for aid in stacking.

26. The apparatus as claimed in claim 24 in which means are provided fordrawing the two half webs prior to passage to said sheeter formaintaining tension therein at said sheeter.

27. The apparatus as claimed in claim 23 in which said accumulatingmeans includes a bin slanted downwardly away from said sheeter anddisposed to receive the sheet pairs discharged therefrom by gravity.

28. The apparatus as claimed in claim 27 in which the bin is laterallyshiftable to enable quick replacement thereof by a second bin when saidfirst bin has accumulated a desired amount of sheets.

29. The apparatus as claimed in claim 23 in which said slitting meanscomprise two knives, a first knife for cutting the web at the center anda second knife for trimming along one edge a predetennined distance fromthe first knife to enable establishment of lateral edge references forthe resulting half webs.

30. The apparatus as claimed in claim 23 in which said turning bars arearranged at an angle to the movement of the half webs before turning,one being spaced from the other perpendicularly relative to the movementof the half webs before turning, each half web being directed to engageover one turning bar but at difierent levels, and both half websthereafter moving in a direction angled relative to their direction ofmovement before turning.

1. The method of making honeycomb core structure in a stack suitable forfurther processing by at least expanding the same, which comprises: A.imprinting parallel lines of adhesive transversely of an elongatesubstantially continuously moving web of flexible material suitable formaking honeycomb core structure, said parallel lines i. being imprintedas two spaced side by side patterns, each pattern being continuous alongthe length of the web, occupying substantially half of the lateral widthof the web, and being disposed only on one face of its respective halfwidth with the back of said half width being unprinted, ii. each patternhaving its lines staggered with respect to the lines of the otherpattern along the length of the web, B. dividing the web substantiallyalong the center to form two half webs each provided with one of saidpatterns only on one face thereof, C. directing the two half websangularly one relative to the other divergingly and then convergingly tomove same into surface to surface engagement one over the other with thepattern carrying face of one half web engaged with the unprinted back ofthe other half web but maintaining the said staggered disposition of thelines of one pattern with respect to the lines of the other patternsubstantially unaltered, D. cutting equal lengths of the two webssimultaneously at a predetermined repeat location to provide pairs offace-to-back sheets of said flexible material of substantially half thewidth of the said original web, E. accumulating and stacking said pairsof sheets into a stack while maintaining at least the same cut ends ofeach pair as a reference for said stack.
 2. The method as claimed inclaim 1 in which the two patterns are disposed on the same face of themoving web.
 3. The method As claimed in claim 1 in which the directionof movement of at least one of the half webs is changed after divisionto convert the moving half webs from side-by-side disposition to adisposition which will bring them into said face-to-back engagement. 4.The method as claimed in claim 2 in which said dividing is accomplishedby slitting, and in which said directing is effected by diverting atleast one of said half webs independently of the other to convert theside-by-side disposition of said half webs to dispositions which willbring them superposed into said face-to-back engagement, one of saidhalf webs being laterally shifted relative the other.
 5. The method asclaimed in claim 4 in which both half webs are turned on differentlevels and in which the half webs are brought into face-to-backengagement both moving in a directional path that is angular withrespect to the path of both half webs prior to the diversion of either.6. The method as claimed in claim 4 in which only one of said half websis turned whereby the directional path of both half webs when in saidface-to-back engagement is not substantially different from the laterallocation of the path of the unturned half web after dividing.
 7. Themethod as claimed in claim 1 in which said web is perforated prior todividing along the same respective edges of both patterns with theperforations lying in a line spaced from said one pattern equally alongthe length of said web and with the perforations equally spaced aparteach perforation having a companion located at an identical point alongthe length of the web but laterally spaced from itself whereby therewill be pairs of perforations along the length of the web, and theperforations having a repeat grouping that recurs at a rate capable ofbeing synchronized with the said repeat locations at equal points alongthe length of the web, the perforations of each cut sheet also aligningwith the perforations of its companion forming the pair of sheets sothat when said pairs of sheets are cut at one of said points, theperforations of any one pair will be registrable with the perforationsof all other pairs to enable alignment by spindling during stacking. 8.The method as claimed in claim 7 in which the perforating is done beforeimprinting.
 9. The method as claimed in claim 7 in which the perforatingis done after imprinting.
 10. The method as claimed in claim 4 in whichthe said web is perforated prior to dividing along similar edges of therespective patterns, there being a line of individual perforations alongeach such similar edge, the perforations being identically equallyspaced along the length of the web and located at identical points alongthe length so that each perforation has an identical perforation spacedlaterally thereof to form therewith a pair, one of each pair ofperforations being alongside of the respective patterns, the perforationpairs having a repeat grouping that recurs at a rate capable of beingsynchronized with the said repeat locations at equal points along thelength of the web, so that when said pairs of sheets are cut at one ofsaid points, the perforations of any one pair will be registrable withthe perforations of all other pairs to enable alignment by spindlingduring stacking.
 11. The method as claimed in claim 4 in which saidslitting is effected by slitting along two lines, one slit line beingspaced laterally a predetermined distance from one edge of the web andhaving one pattern between it and said edge and located between the twopatterns, the other slit line being substantially the same predetermineddistance from the one slit line and having the second pattern between itand the first slit line and being closely adjacent to the second edge ofthe web, whereby the cut sheets of each pair will be substantially thesame width notwithstanding lateral drift of the web.
 12. The method asclaimed in claim 10 in which the line of perforations of one pattern islocated adjacent one edge of said web between said one pattern and saidone edge, and the line of perforations of the other pattern occursbetween the said other pattern and the center of said web whereby whenso slit, each half web will have one line of perforations along thesimilar edge thereof.
 13. The method as claimed in claim 12 in whichsaid slitting is effected by slitting along two lines, one slit beingspaced laterally a predetermined distance from said one edge of said webwhereby to have said one pattern and one line of perforations between itand said one edge and being located substantially at the center of theweb between the two patterns, the other slit line being substantiallythe same predetermined distance from the one slit line and having thesecond pattern and second line of perforations between it and the firstline and being closely adjacent the second edge of the web, whereby thecut sheets of each pair will be substantially the same widthnotwithstanding lateral drift of the web.
 14. The method as claimed inclaim 13 in which the said one edge and second slit line of each pair ofsheets are used as lateral references in stacking said sheets.
 15. Themethod as claimed in claim 14 in which said sheets are jogged whilestacking.
 16. The method as claimed in claim 15 in which said sheets arespindled into at least one perforation of each sheet at an end thereofduring stacking and jogging.
 17. The method of making honeycomb corestructure in a stack suitable for further processing by at leastexpanding the same, which comprises: A. imprinting parallel lines ofadhesive on the face and transversely of an elongate substantiallycontinuously moving web of flexible material suitable for makinghoneycomb core structure, said parallel lines being arranged in twoindependent patterns on respective lateral halves of the web with thelines of one pattern staggered relative to the lines of the other, B.slitting the web up its center to divide the same into two half websmoving side by side, C. turning the half webs relative to one anotherdiverting at least one first in a plane diverging relative the other andthen in a plane converging relative the other so as to bring the halfwebs into laterally aligned face to back engagement with one anotherwith the face of one engaging the back of the other, D. cuttingpredetermined lengths of the engaged sheets simultaneously, E.accumulating the sheets to form a stack of aligned sheets referencedfrom a cut end thereof.
 18. The method as claimed in claim 17 in whichthe patterns are imprinted on the face of the web only and the back ofthe web is unprinted.
 19. The method as claimed in claim 18 in which theadhesive is resinous and the web is temporarily dried prior to slittingbut is capable of being heated to activate the adhesive to a permanentlyadhering condition after stacking.
 20. The method as claimed in claim 19in which the web is temporarily dried by heating and is thereaftercooled prior to slitting.
 21. The method as claimed in claim 18 in whichthe web is perforated prior to slitting along a pair of lines ofperforations, each line being spaced laterally of one another and havingequal spacing along the length of the web, with the individualperforations of one line having identically laterally locatedperforations in the other line, each line being equally laterally spacedrelative to one pattern and having a repeat grouping capable of beingsynchronized with the repeat of the patterns to enable the use of saidperforations for registration during stacking.
 22. The method as claimedin claim 17 in which the back of the web is imprinted with the identicalpatterns but each back pattern is staggered with respect to the patternon its face half and with respect to its companion pattern on back halfof the web, and in which a blank web is laminated to one of the face orback before slitting.
 23. Apparatus for making honeycoMb from flexiblesheet material, comprising: A. means for mounting a roll of raw sheetmaterial and feeding and guiding the same in a substantially continuousmovement through said apparatus, B. a printing station for applyingadhesive lines to said web and comprising a printing roll having axiallyextending printing lines in two axially spaced continuous patterns withthe lines of said patterns staggered one relative to the other wherebyto print two side by side patterns staggered on one surface of said webas it passes said printing station, C. a drying station having theimprinted web passing through the same, and serving to dry temporarilythe adhesive imprinted thereon, D. a slitting station having means forslitting the web up its center to form two half webs, each with apattern on one face thereof and being blank on the back thereof, E. aturning station for angularly diverting at least one of said webs tochange the side by side disposition of said half webs to a laterallyaligned face to back disposition, said turning station including atleast one pair of half web direction-changing turning bars and at leastone of said half webs being directed to move divergingly from the otherand thereafter turn to shift laterally and convergingly relative to theother, F. means for laminating the two half webs in said face to backengagement with the imprinted face of one engaging the blank back of theother, G. a sheeter receiving the laminated half webs from thelaminating means and arranged to cut the same simultaneously inpredetermined lengths and discharging same in pairs and, H. means foraccumulating the cut sheets for stacking.
 24. The apparatus as claimedin claim 23 in which means are provided for adjusting the relationshipof said patterns to maintain their original staggered relationship alongtheir lengths after having been separated by slitting and prior tolaminating.
 25. The apparatus as claimed in claim 24 in whichperforating means are provided for applying a line of perforationsadjacent each pattern along the same edge thereof prior to slitting sothat each half web has a line of perforations for aid in stacking. 26.The apparatus as claimed in claim 24 in which means are provided fordrawing the two half webs prior to passage to said sheeter formaintaining tension therein at said sheeter.
 27. The apparatus asclaimed in claim 23 in which said accumulating means includes a binslanted downwardly away from said sheeter and disposed to receive thesheet pairs discharged therefrom by gravity.
 28. The apparatus asclaimed in claim 27 in which the bin is laterally shiftable to enablequick replacement thereof by a second bin when said first bin hasaccumulated a desired amount of sheets.
 29. The apparatus as claimed inclaim 23 in which said slitting means comprise two knives, a first knifefor cutting the web at the center and a second knife for trimming alongone edge a predetermined distance from the first knife to enableestablishment of lateral edge references for the resulting half webs.30. The apparatus as claimed in claim 23 in which said turning bars arearranged at an angle to the movement of the half webs before turning,one being spaced from the other perpendicularly relative to the movementof the half webs before turning, each half web being directed to engageover one turning bar but at different levels, and both half websthereafter moving in a direction angled relative to their direction ofmovement before turning.